Strain-rate-dependent mechanical properties of the equine hoof wall.

The research studies how the mechanical properties of horse hooves react under different loading rates to understand if the hoof wall’s viscoelasticity affects its ability to withstand fractures and tension. Results showed that most tensile parameters, except ultimate strain, were sensitive to strain rate and the toughness against fractures remained unchanged, even at high strain rates.

Research Objective and Methods

• The study aimed to understand the impact of different loading rates on the mechanical properties of the equine hoof wall, particularly their effect on fracture toughness and tensile parameters.
• The hoof walls of horses were subjected to different loading rates in a compact tension (CT) fracture, tensile, and three-point bending dynamic tests.
• The tests were conducted using four cross-head rates in CT tests and four strain rates in tensile tests.

Tests and Findings

• In CT tests, both the initial modulus (Ei) and the stress intensity factor (K) increased as the strain rate went up.
• The fracture toughness parameter (J) remained constant, irrespective of the level of strain rate.
• In tensile tests, all parameters, excluding the ultimate strain, were sensitive to the rate of strain. The Ei, total energy required to break, and maximum stress all increased along with the strain rate.
• Results from low-amplitude dynamic tests matched the Ei trends observed from CT and tensile tests.

Microscopic Examination and Final Observations

• Through the depth of the hoof wall, the direction of crack growth varied, presenting a trilaminar ply-like pattern.
• Scanning Electron Microscope (SEM) inspections of fracture surfaces showed a decrease in pseudo-ductile behavior with an increasing rate of strain.
• Despite these findings, the study concluded that the viscoelasticity of the equine hoof wall doesn’t seem to negatively affect its fracture toughness, even at high strain rates.

The research provides an in-depth understanding of how the mechanical properties of horse hooves respond under different levels of strain. While most parameters showed sensitivity to the strain rate, the toughness of the hoof against fractures remained unchanged. These findings could be vital in understanding potential treatments or protective methods for the hooves of equines in different sporting or work environments.